Production of artificial yarns, foils, and similar materials



April 1942- R. w. MONCRIEFF ETAL I 73 PRODUCTION OF ARTIFICIAL YARNS, FOILS, AND SIMILAR MATERIALS Filed March 8, 1940 RM). W W

" (.RW. gavm'monS .SWMML A'Hormq s -Patented Apr. 14, 1942 ST E S QFFICE PRODUCTION OF ARTIFICIAL YARNS; I

FOILS, AND S l MATERIALS corporation of Delaware Application March a, 1940, Serial No. 322,948 In Great Britain March 9, 1989 Claims. (Cl. 8-132) This invention relates to improvements in the stretching of artificial yarns, foils and similar materials.

British specifications, Nos. 438,584 and 438,585 and U. S. Patents Nos. 2,142,717 and 2,142,722 describe processes for improving the properties of yarns, foils and similar materials having a basis of cellulose esters or ethers by stretching them in the presence of steam during their travel from one point to another.

It has been discovered that improved results, particularly as regards extensibility of the products, may be obtained in processes of the above character if the materials, particularly yarns made of cellulose acetate or other organic derivative of cellulose, are conditioned in wet'steam prior to the stretching operation. This conditioning treatment is particularly effective when the stretching operation itself is carried out in steam which is dry or substantially dry. The invention includes not only stretching processes in which the materials are conditioned, but also apparatus for carrying out the processes. 7

' The most satisfactory method of carrying out the conditioning operation is, in general, to effect it while the yarn or other material is in package form and while it is being drawn from the package and proceeding to the stretching vess'el, since in this manner as the package is unwound, fresh layers of the material are continually being exposed to the conditioning'agent so that uniform conditioning of the materials is facilitated. The conditioning may be assisted by immersing the packages in hot water for a short time, e. g. 5-10 minutes, beforeexposing them to the wet steam. From the conditioning apparatus the materials may pass to a positivelydriven feed device and through the stretching chamber in which they arestretched by means of a positively driven stretching-device adapted to draw the materials through the stretchingchamber at a speed-greater than that at which they are forwarded by the feed device. In order to moisten the materials thoroughly before they enter the stretching chamber, particularly if the steam employed for stretching is dry or substantially'dry, they may pass through a bath of water or in contact with a Wick or fabric-covered roller or other device which supplies water to them.

The apparatus according to the invention comprises a container for a package of the material provided with an inlet for wet steam and an outlet for the material in combination with a positively-driven feed device, a substantially closed chamber having an inlet for stretching medium and an inlet and an outlet for the materials and a positively driven stretching-device adapted to draw the materials throughthe stretching-chamber ata speed greater than that at which they are forwarded by the feed device.

A sectional elevation of an apparatus in accordance with the present invention is shown diagrammatically in the accompanying drawing. The apparatus comprises a container l for a package !9 of yarn or other material to be treated. This container is provided with a steam inlet 2, a drain 3, and a cooling chamber 4, which is provided with an inlet 5 and an outlet 6 for cold water. The drain 3 projects into the container so that a layer of condensed steam may be maintained in the container, whilst the steam inlet 2 is so arranged that steam entering the container has to pass through this layer of water. The container has a small hole 20 in order to maintain atmospheric pressure within the container and it is provided with an outlet 1 for the yarns or other materials being treated. This outlet projects above the level of the top of the drain 3 so that the materials passing out of the container do not come into contact with the layer of water.

From the container the materials pass to a feed roller 8 and then over a roller 9 by. which the roller 8 is driven. The centre portion of the feed roller is grooved so that the yarns passing round the roller do not come into contact with the driving' roller 9. The rollers 8 and 9 are carried on bearings 2| which are capable of beingmoved so as to separate the rollers.

From the feed roller the materials pass into .a stretching chamber 10 which is provided with inlet and outlet orifices II and [2. A small cup 13 is provided round the inlet orifice, which is kept filled with water, so that the materials are moistened before they enter the stretching chamber. If the cup is made of a polymerized phenylformaldehyde resin or other material of low heatconductivity the steam issuing from the stretching chamber condenses, and maintains a layer of water in the cup extending up to the level of a drain [4. Steam enters the stretching chamber through a pipe l5. After issuing from the stretching chamber, the yarn passes round a stop motion bar l6 and then on to a cheese ll, which is surface-rdriven by a roller ill at a higher periph- Instead of using a cheese or other package as a stretching-device,

a separate positively-driven stretching-roller may be provided after the stretching chamber and the materials may pass from this roller to 'a take-up device.

Steam for the container and stretching chambers is taken from a main steam supply through the branch line 22. A steam trap 23 is provided which communicates with the stretching chamber.

An apparatus such as that described above takes up a comparatively small amount of space V and a number of units of this construction may be arranged side by side. In this manner a number of yarns maybe stretched simultaneously, with the advantage that the breakage of one end or any other cause which interferes with the functioning of one unit does not aflect the operation of the remaining units;

Steam may be fed directly to the different units from the main steam supply, but preferably a steam container of fairly large volume is interposed between the steam supply and the units, which assists in maintaining the steanr condi-. tions uniform throughout the stretching operation and among the difierent units. When it ,is desired to use dry steam, steam traps may be inserted at suitable points along the steam lines and in the stretching chambers in order .to remove any condensed water.

In stretching yarns and other articles according to the process of the present invention steam may be used at a temperature of, for example, 110, 120 or 140 C. or more.

The best temperature to employ depends upon the other conditions existing, for example the nature of the materials to be stretched, and particularly upon thedegree of stretch which it is desired to efiect, the higher the degree of stretch required, the higher, in general, being the steam temperature necessary. Moreover, in general, dry steam appears to require a somewhat higher temperature than wet steam to effect the same them 'while they Pass through an atmosphere containing dry steam. 4

2. Process for the treatment of artificial filaments, foils and similar materials having a basis of an organic derivative of cellulose, which comprises drawing them from; a package positioned in an atmosphere of wet steam and stretching them while they pass through an atmosphere containing dry-steam at a temperature of at least 110 C.

3. Process for the treatment of artificial filaments, foils and similar materials having a basis of an organic derivative of cellulose, which comprises drawing them from a package positioned in an atmosphere of wet steam, moistening the materials by passing them through water and then stretching them while moist while they pass through an atmosphere containing dry steam.

4. Process for the treatment of artificial filaments, foils and similar materials having a basis of cellulose acetate, which comprises drawing ,them from a package positioned in an atmosphere degree of stretch. Yarns and similar materials a may be stretched, for example, to 150, 1'70, 200,-

500% or even more of their original length and their tenacity may be doubled or trebled or increased to an even greater extent.

The present invention is particularly valuable in the stretching of yarns made of continuous filaments of the ordinary acetone-soluble cellulose actate, but it is also applicable to other materials having a basis of other cellulose esters and of wet steam and stretching them' while they pass through an atmosphere containing dry steam.

5. Process for the treatment of artificial filaments, foils and similar materials having a basis of cellulose acetate, which comprises drawing them from a package positioned in an atmosphere of wet steam, moistening the materials by passing them-through water and then stretching them while moist while they pass through an atmosphere containingv dry steam.

ROBERT WIGHTON' MONCRIEFF. CHARLES WILLIAM SAMMONS. 

